The last time I met Kenneth Thomson, Lord Thomson of Fleet, who has died aged 82, was towards the end of the year-long dispute at the Times in 1979. It was a defining moment in his life as a newspaper baron in Britain. He bore all the signs of a saddened, perhaps defeated, man, although none of us then knew just how sad the scene was eventually to become.

The Times had not been thundering - or even squeaking - for a year, during which Margaret Thatcher had become Britain's first woman prime minister. The strike was settled in November 1979, a few weeks after my interview with Thomson in his office at Gray's Inn Road, where the Times and Sunday Times were then housed. Fourteen months later, the news broke that the Thomson family had sold out to Rupert Murdoch, a decision taken by Ken Thomson himself, against much advice from his management team.

He had had enough. The journalists' strike in August 1980, long after the printers' dispute had been settled, finally convinced him that the situation was hopeless. He saw the deal with Murdoch as a swift, clean break from all the haggling, political wrangling and backstage manoeuvres. He wanted "out" - just as much as Rupert wanted "in". Once a conditional agreement was reached in January 1981, Thomson retreated to his native Toronto to resume the life he had always preferred.

His father, Roy, the first Lord Thomson of Fleet, had died in 1976, and there are some who say that Kenneth, who revered his father, never fully reconciled himself to life in Britain after the death. In fact it became clear that Kenneth - the second Lord Thomson of Fleet when he was in the UK but plain Mr Thomson in Canada - had long ago decided to pull out. In retrospect, that glazed look of the defeated man I interviewed revealed more than one realised. The bitter strike that stopped the Times for a record period was to prove the Rubicon for Fleet Street. In his bloodstream, perhaps Thomson even sensed it.

What it did do was hand him the opportunity to re-start his life in Canada, where the family fortune, created by his father, was already legendary. Thomson was born in Toronto - as was his father - the only son of Roy Thomson and his wife, Edna Alice Irvine. He went to the Upper Canada College before graduating from Cambridge with a good MA. He served with the Royal Canadian Air Force during the second world war, and afterwards started in the editorial department of the Timmins Daily Press, Ontario, where Roy himself had started out in 1934, acquiring his first newspaper - the Timmins Daily Press.

Kenneth worked in virtually every department of the paper, as a reporter, advertising salesman and general manager, a process he repeated in a number of other Thomson newspapers in Ontario before moving into the Toronto head office in the '1950s, to take charge of the group's Canadian and American operations.

By then Thomson Newspapers was the most powerful media group in Canada, owning more newspapers than any other organisation. This also was about the time, 1953, that Roy acquired his first UK newspaper, the Scotsman in Edinburgh. Indeed, in 1954 he moved to Scotland, setting up Thomson Newspapers HQ in Britain and leaving Kenneth to run the Canadian empire. Roy then set about taking over a huge network of British regional newspapers, mainly by acquiring the Kemsley Group, whose stable included the Sunday Times.

He made successful bids for commercial television franchises, notably in Scotland, and bought into book publishing and travel companies, creating Thomson Travel. In 1964 Harold Wilson gave him a hereditary peerage, and in 1967 he acquired the Times. Everything, appeared to be at his finger tips - and within the grasp of his son Kenneth.

But Kenneth Thomson did not share his father's zeal for newspaper acquisitions. He was a shy, reserved, somewhat detached man with few traces of his father's bouncing, gregarious personality. He cared very much about people and was an exceptionally intelligent manager; but his real interests lay in the arts. He began seriously to collect paintings, art antiques, such as medieval bronzes, reliquary chests and sculptures, in the early 1960s. When he came to live in London, he established a close relationship with a well-known art dealer, Herman Baer. Collecting pieces of rare art became his passion; most of the Thomson collection is now in a Toronto gallery.

In 1996 he bid successfully at an auction for the St Thomas-a-Becket chasse, circa 1170. The price was £4.18m. But he then withdrew the bid to allow the copper gilt reliquary chest to remain in Britain. It was bought eventually by the National Heritage Memorial Fund, to which Lord Thomson was a donor. It was very much Kenneth's salute to Britain despite his disappointments.

In his later years, certainly from the mid-1980s when he was firmly back in Toronto, Kenneth Thomson started to move the company away from newspapers and conventional media towards new technology-based communications in Canada and the United States. He concentrated on educational technology, legal publishing, scientific information for research and development, healthcare systems - indeed anything with a new technology link.

Gradually the old Thomson empire was sold off in packages - many local newspapers in Canada, as well as Thomson newspapers in the UK. In 1989 the group disposed of its interests in North Sea oil; the hugely successful Thomson Travel organisation was sold in 1998 for more than £1.3 bn. By 1993 the Canadian base of Thomson newspapers had been re-structured with new strategic groups formed to re-direct the company's focus. It was already a very different ship from the vessel launched by Kenneth's father. One thing the family retained was the Toronto Globe and Mail, once the flagship of the newspaper empire and in which the Thomson Corporation still retains a 20% stake.

Kenneth Thomson was reputed to have been one of the world's dozen or so richest men. His personal fortune has been estimated at £9.5bn. Yet to the end he preferred the quiet, modest life without lavish living. He did not go in for mansions round the world, yachts or racehorses. He was a non-drinker and non-smoker, and favoured long walks in the Canadian countryside. He never took up his seat in the House of Lords.

His passion for collecting exceptional works of art, sculptures as well as paintings, never ceased: nor did his generosity in donating rare works from his collection to Canadian art galleries. In 2002 he handed over most of his multi-million dollar collection of European and Canadian paintings and sculpture to the Art Gallery of Ontario - a collection that included Rubens' Massacre of the Innocents. At the time he promised further huge donations and loans to the Toronto gallery, and agreed to donate in trust an estimated 2,000 works, a gift unprecedented in Canadian history.

Earlier that year Kenneth passed on the family business, the Thomson Corporation, to his son David, who became the new chairman of the board. Like his father, David Thomson possesses his own large collection of paintings by a range of great artists, among them Constable, Munch, Picasso, Turner and Rothko.

Kenneth was regarded by some as an eccentric, shy and somewhat "grey figure". By the standards of Rupert Murdoch, certainly by those of Robert Maxwell, he was. But when people joked about his ordinariness, he would respond by referring to his father: "Even though he spoiled me in a material sense, he ingrained in me a sense to do things properly and responsibly."